Hi Lee, i think that it is not possible ! The prefs.js file contain all changes you made, but not all about:config preferences.

A brief guide to Mozilla preferences

Another option is to create a user.js file, and make your changes there. If an option cause you problems or you don't want it anymore then delete it from user.js file.

Note that firefox, when you open it, first read from the user.js file, that means user.js entries will override every default preference referred.

thank you

Prefs that have the default value don't need to be saved and deleting (removing) the prefs.js file that stores modified (user set) prefs is enough to undo all changes and reset all prefs to the default value.

Hi ideato,

Thank you for your answer with the helpful links. I'll have to read up on them to make more sense of it all since this is new to me.

Correct me if I'm wrong but if I create a user.js file then copy any default settings from about:config and paste them into the user.js file, edit the setting, it will get read from the user.js first so if there is a duplicate entry in about:config with the old setting, the old setting will get ignored? Since you said "user.js entries will override every default preference referred", that's why I ask to make sure that's what I got from what you said.

I want to try out these different tweaks that I learn about from various websites and YouTube videos to speed up Firefox and reduce the RAM usage. I want to experiment but put things back to normal if need be.

Thanks again.

Hi cor-el,

Thanks for your answer. I will test that out on a Firefox browser that's in a virtual machine I have so as not to mess up my host's Firefox. I'll make some changes in about:config and then delete the prefs.js file to see if the changes go away.

If I delete the prefs.js file, does Firefox automatically create a new one with all the default values back in place?

Hi Lee.

......Correct me if I'm wrong but if I create a user.js file then copy any default settings from about:config and paste them into the user.js file, edit the setting, it will get read from the user.js first so if there is a duplicate entry in about:config with the old setting, the old setting will get ignored? Since you said "user.js entries will override every default preference referred", that's why I ask to make sure that's what I got from what you said.......

Yes you are correct.

thanks again

The prefs.js file stores user set values of prefs, so if you delete this file then all prefs are automatically reset to the default value. The user.js file is read after the prefs.js file has been read and thus overrides settings from the previous sessions that have been stored in the prefs.js file.

These add-ons can be a great help by backing up and restoring Firefox

FEBE (Firefox Environment Backup Extension) {web link} FEBE allows you to quickly and easily backup your Firefox extensions, history, passwords, and more. In fact, it goes beyond just backing up -- It will actually rebuild your saved files individually into installable .xpi files. It will also make backup of files that you choose.

OPIE {web link} Import/Export extension preferences

Hi ideato,

Thank you for confirming that for me. I think I might understand now.

Thank you cor-el. I'm sorry but I am now confused. You said "The user.js file is read after the prefs.js file has been read" which is the opposite of what ideato told me, unless I misunderstood which is quite possible.

And if I delete the prefs.js file, will a replacement prefs.js file be created (with the default settings in it) the next time Firefox is opened? If it's not created, then to me, anything inside a user.js file will override a default setting. ?

Thanks, and I appreciate your patience while I try to wrap my head around all this. I was just hoping the settings would be stored in one file that I could backup but it's not and now, it's twisting my head into knots trying to make sense of it all. :)

Hi FredMcD. Thank you so much for the add-on suggestion. I am looking into that right now. I've been reading some reviews on FEBE and it looks promising. Am I also supposed to install OPIE to go along with FEBE?

I'll test it out on Firefox in a virtual box machine. Might be a couple days but I'll let you know how it goes. Thanks again.

OPIE will save the settings for the add-ons.

FEBE saves add-ons, settings (program only) password, and so on.

Using both can restore Firefox to what it was, even after a reset.

Thank you, FredMcD.

I'll go with using the add-ons FEBE and OPIE since that seems to be the simplest and only solution for now. I have so many add-ons already installed and adding more of them is just going to cause Firefox to eat up more memory, which I have plenty of, but more add-ons usually means it'll slow Firefox down and the whole meaning behind my trying to backup Firefox is to try out various about:config tweaks to speed up Firefox and restore it back to the previous, before the tweak state, if need be.

I'll eventually find out what the deal is with the prefs.js file and user.js file (like which one is actually read first and which overrides which) one of these days but until then, the add-ons you suggested are the solution I'll go with to hold me over. Thanks again.

The prefs.js file stores the values of prefs that have been modified, so if you delete this file and a possible user.js file then all prefs automatically get the default value.

Follow this advice;

• 1) Don't have more than one add-on for the same job. If you have more, pick one. Note: some add-ons work together.

• 2) Disable any add-ons that you aren't using. Only turn them on when you need them.

Thanks for your reply cor-el. I do understand that if those files are deleted, everything goes back to default, that part is clear to me.

You previously told me "the user.js file is read after the prefs.js file has been read" but ideato replied to me saying "Note that firefox, when you open it, first read from the user.js file, that means user.js entries will override every default preference referred" which seems to be the opposite of what you said so that left me confused. I'm honestly not calling anyone a liar or anything of the sort, I'm just in need of knowing which file gets read first.

I was under the impression that I could copy and paste any setting from about:config into a new user.js file, change the setting to the tweak I'm trying out, and it would read the setting from the user.js file first before the prefs.js file. And if a setting in the user.js file didn't work out, I could just remove that setting from within the user.js file and it would revert back to the default setting.

Great advice, FredMcD. Thank you. I do try to keep the add-ons at a minimum and remove some that I don't use. I'm big on privacy and security so I have some privacy-enhancing ones running and some to increase productivity.

I have nine add-ons installed, no two do the same job. Is that too many you think? What would be considered too many? Like 20 or so? Thanks.

I once saw a system details for a user, I think it had 50 add-ons. May add-ons are full time, while others work only when you call them. You can leave some of those disabled until you need them. For example, I have an add-on that will check the bookmark for any problem. Like dead links or duplicates. I leave them disabled.

BTW, about FEBE, I set it up to backup each day and to keep 30 days of backup files. OPIE I run once or twice a week.

What is important is that settings in user.js prevail over settings from the previous session that were stored in the prefs.js file, so when you (re)start Firefox you get what you specify in user.js and you lose what had been stored in the prefs.js file the previous time you closed Firefox.

Wow, 50 add-ons seems to be way too many! I can't imagine how much memory is being used up when Firefox is running on that computer, or how much it's slowing it down.

I'm wondering though, do add-ons that aren't active still use up memory? I'm talking about those sitting dormant, that do nothing until called upon such as one that takes a full-paged screenshot whenever I need one.

And sorry for the delayed response, been out of town since last Friday and don't have much time for getting on my laptop while I'm away.

Thanks for your responses, especially for telling me about scheduling FEBE to run daily and running OPIE once or twice a week. I think I'll do it that same way, it makes sense.